The application requests continued support for selected students enrolled in a multi-disciplinary predoctoral training program, "Neural and Endocrine Regulation of Brain and Behavior," administered by MIT's Department of Brain and Cognitive Sciences. The program trains students to conduct research in neuroscience and behavior, specifically focusing on the molecular and cell biology of synaptic transmission, plasticity, and their modulation (the effects of circulating chemicals [e.g., nutrients, drugs, hormones, toxins] on neurotransmitters and other brain constituents that underlie particular behaviors. The faculty in the program have expertise in a variety of neuroscience research areas such as molecular neurobiology, genetics, neuropharmacology, neurophysiology, neuroanatomy, biophysics, and psychophysics. The program has graduated 22 doctorates since the last competing continuation; four of these trainees received support from this grant. We request continued support for three predoctoral trainees. Trainees take courses that satisfy departmental requirements for a major in Neuroscience (and a minor in Neurobiology). In addition, they are required to take courses in molecular neurobiology, animal behavior, advanced biochemistry and physiology of neurotransmitters and receptors, and endocrinology [or nutrition] or general pharmacology. They are also encouraged to learn about normal and pathological human behaviors by taking appropriate courses or seminars and by participating in research at MIT's Clinical Research Center. Trainees will, in general, have strong backgrounds in the natural sciences (e.g., undergraduate majors in biology, chemistry, physics, or electrical engineering). Occasional trainees will already hold a graduate degree in another field such as medicine. Candidates for appointment to one of the funded slots will be chosen by the faculty committee constituted for the purpose of overseeing this program and will be evaluated on the basis of interviews, talent for research as demonstrated by past performance, letters of recommendation, grades, and GRE scores.